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Modeling Of Earth Abundant Oxide Nanoparticles To Guide Materials Design For Energy Applications
No full textComplex materials are vital in our transition to a sustainable energy future playing a key role in a variety of applications including catalysis and batteries. Transition metal oxides belong to this complex class of materials and can be synthesized in a variety of unique ways leading to distinct properties. Understanding why changes in structure lead to changes in a material’s performance, is important to help improve materials design as the need for new energy solutions is urgently needed. Research is focused on using materials with earth abundant metal components, to have the materials design done sustainably and economically. Cobalt oxide is a versatile material that is used in a wide range of applications such as electrocatalysis and Li-ion batteries. The goal is to further improve its performances through different design techniques, such as nanostructuring and doping. Here, density functional theory (DFT) is used to study well-defined, but complex, nanoparticle structures to understand their performance and guide the design, of new and improved materials.
This thesis focuses on DFT modeling of nanostructured and doped cobalt oxide based materials as electrocatalysts for the oxygen evolution reaction (OER) and as cathode materials for Li-ion batteries. The computational predictions and findings ofthis thesis provide a fundamental understanding of and the link between the structure and performance of the material at the atomic scale which cannot be achieved by experiment alone. For the OER nanostructured supported Fe-doped cobalt oxide electrocatalyst materials, a computational framework is established and it is identified that a site-specific understanding of the activity is needed to explain the experimentally observed activity trends as well as provide insights for improved materials designs. For the Li-ion cathode material, a similar framework as for the OER elecrocatalysts is used to study the electrochemistry of doped LiCoO2. The role of the dopants on the performance of the battery is examined as well as how the doped structures may change the cathode electrolyte interface. This thesis demonstrates the importance of modeling the details of complex nanostructured electrochemical systems and their interfaces and concludes that site-specific understanding of materials is necessary to explain observable experimental trends and predict new chemistries not accessible by current experimental techniques
Unlocking Compacted Heterochromatin Through Modulation Of Associated Proteins
Get PDFThe hundreds of cell types that compose human body tissues contain identical genomes yet vary considerably in their gene activity and protein content. While the underlying blueprints that define these diverse cell types exist in all cells, a given cell’s specific transcriptomic and proteomic landscape is controlled by an incredibly complex system of gene regulatory complexes and epigenetic marks which promote activation of cell-type specific gene expression profiles and silence alternative cell fate genes. However, the mechanism by which specific genomic loci are silenced in different cell types is still not well understood. Here I strove to understand the vital contribution of tightly compacted heterochromatin on cell identity at specific loci. I studied how 97 unique heterochromatin-associated human proteins play a role in heterochromatin-based gene and repetitive element silencing. As H3K9me3 can block cellular reprogramming, we used a human-induced fibroblast to hepatocyte (hiHep) reprogramming model to uncover diverse genes and repetitive elements silenced by each protein. We conducted RNA-seq experiments both with and without the addition of hiHep reprogramming factors. We identified four unique clusters of these proteins based on their common targets of repression, including differences in H3K9me3 and H3K27me3 marks across genes derepressed by each cluster. In an additional study, I investigated how KRAB domain-containing zinc finger proteins (KRAB-ZFPs) might silence hepatic genes in alternate lineages. I identified six putative liver lineage antagonistic KRAB-ZFPs. A mostly unstudied primate-specific KRAB-ZFP known as ZNF695 became the top candidate for allowing hundreds of genes, including hepatic genes, to be derepressed following knockdown in the hiHep reprogramming model and facilitated the widespread loss of H3K9me3. I mapped ZNF695 localization throughout the genome and tied these patterns to the observed gene expression changes. Additionally, we were able to see that depletion of ZNF695 in hiHeps transplanted in a diseased liver mouse model were able to produce higher levels of human albumin that hiHeps without the knockdown. Together, these findings greatly expanded our knowledge of H3K9me3-based repression in humans and provided a novel picture of ZNF695 regulatory capabilities
Regulation Of The Tubulin Code In Cardiac Hypertrophy And Failure
Get PDFA proliferated and post-translationally modified microtubule network underlies cellular growth in cardiac hypertrophy and contributes to contractile dysfunction in heart failure. Yet how the heart achieves this modified network is poorly understood. Determining how the “tubulin code” – the permutations of tubulin isoforms and post-translational modifications – is rewritten upon cardiac stress may provide new targets to modulate cardiac remodeling. Further, while tubulin can autoregulate its own expression, it is unknown if autoregulation is operant in the heart or tuned in response to stress. Here I use heart failure patient samples and murine models of cardiac remodeling to interrogate transcriptional, autoregulatory, and post-translational mechanisms that contribute to microtubule network remodeling at different stages of heart disease. I find that autoregulation is operant across tubulin isoforms in the heart and leads to an apparent disconnect in tubulin mRNA and protein levels in heart failure. I also find that within 4 hours of a hypertrophic stimulus and prior to cardiac growth, microtubule detyrosination is rapidly induced to help stabilize the network. This occurs concomitant with rapid transcriptional and autoregulatory activation of specific tubulin isoforms and microtubule motors. Upon continued hypertrophic stimulation, there is an increase in post-translationally modified microtubule tracks and anterograde motors to support cardiac growth, while total tubulin content increases through progressive transcriptional and autoregulatory induction of tubulin isoforms. My work provides a new model for how the tubulin code is rapidly rewritten to establish a proliferated, stable microtubule network that drives cardiac remodeling, and provides the first evidence of tunable tubulin autoregulation during pathological progression
Anderson-Bernoulli Localization On 2d And 3d Lattice
Get PDFThe Anderson model describes the behaviour of electrons inside a piece of metal with uniform impurity.The Anderson-Bernoulli model is a special case of the Anderson model where the potential has Bernoulli distribution. We consider Anderson-Bernoulli localization on d dimensional lattice for d=2,3. For d=2, we prove that, if the potential has symmetric Bernoulli distribution and the disorder is large, then localization happens outside a small neighborhood of finitely many energies. For d=3, we prove that localization happens at the bottom of the spectrum
Enhancing Strength And Toughness Via Reinforcement With Nanocellulose Fibers
No full textCellulose nanofibrils (CNFs) are a nanomaterial obtained from plant sources and have excellent mechanical properties, high aspect ratios, and biodegradability. As a reinforcing phase, CNFs have the potential to improve mechanical properties of polymer materials. The overarching objective of this thesis is to investigate the use of CNFs to enhance the strength andtoughness of polymers and traditional papers.
In the first part of this thesis, poly methyl methacrylate (PMMA) fibers are reinforced using CNFs to increase the strength and toughness. Fourier transform infrared (FTIR) spectroscopy is used to measure molecular orientation in fibers. Tensile tests and fiber-based fracture tests using edge-cracked fibers are used to quantify the enhancement of modulus, strength, and fracture toughness through the addition of CNFs to PMMA. Specifically, a 2× improvement in fracture toughness is observed at 1% wt. CNF content.
In the second part of the thesis, filter paper, which is a network of microscale cellulose fibers is infiltrated with CNFs to create all-cellulose sheets with heterogeneous mechanical properties. This is realized by printing and subsequent drying of an aqueous CNF solution and patterning of the infiltrated regions is used to engineer the strength and toughness.Single edge notch tension (SENT) tests are performed on the specimens to evaluate their fracture behavior. It is shown that geometric and elastic heterogeneity can be utilized to tune the toughness while maintaining or improving the strength.
Finally, to overcome limitations of SENT, a new experimental fracture specimen, the hinged rigid beam (HRB), was developed. The HRB eliminates the compressive stresses developed in conventional beam-bending fracture tests like the double cantilever beam method, thus making it suitable for testing thin materials such as paper. A mechanics model of the HRB was developed to allow critical strain energy release rate to be calculated from the measured force-displacement response and was validated via finite element analysis and experiments on thin PMMA sheets. This technique was used to characterize the toughness of several materials, including filter paper, copy paper and 2D lattices. Finally, the HRB was used to characterize and understand the fracture behavior of patterned nanocellulose infiltrated sheets
The Design Of A Community-Informed Socially Interactive Humanoid Robot And End-Effectors For Novel Edge-Rolling
Get PDFThis dissertation discusses my work in building an HRI platform called Quori and my once separate now integrated work on a manipulation method that can enable robots like Quori, or any more capable robot, to move large circular cylindrical objects.
Quori is a novel, affordable, socially interactive humanoid robot platform for facilitating non-contact human-robot interaction (HRI) research. The design of the system is motivated by feedback sampled from the HRI research community. The overall design maintains a balance of affordability and functionality. Ten Quori platforms have been awarded to a diverse group of researchers from across the United States to facilitate HRI research to build a community database from a common platform.
This dissertation concludes with a demonstration of Quori transporting a large cylinder for which Quori does not have the power to lift nor the range of motion to dexterously manipulate. Quori is able to achieve this otherwise insurmountable task through a novel robotic manipulation technique called robotic edge-rolling. Edge-rolling refers to transporting a cylindrical object by rolling on its circular edge, as human workers maneuver a gas cylinder on the ground for example. This robotic edge-rolling is achieved by controlling the object to roll on the bottom edge in contact with the ground, and to slide on the surface of the robot\u27s end-effector. It can thus be regarded as a form of robotic dexterous, in-hand manipulation with nonprehensile grasps. This work mainly addresses the problem of grasp planning for edge-rolling by studying how to design appropriately shaped end-effectors with zero internal mobility and how to find feasible grasps for stably rolling the object with the simple end-effectors
Developing Pedagogical Content Knowledge For Stem Integration Through Data Literacy: A Case Study Of High School Science Teachers
Get PDFIn our data-rich world, there are strong calls for greater focus on data literacy as increasingly, 21st century jobs require some level of data literacy. Data literacy is inherently STEM integration, especially when working with real-world scenarios, as it requires bringing math and technology into the science classroom to interpret and engage with authentic data. Since teachers are often trained in one specific subject, they need additional support to accomplish STEM integration. In addition to subject matter knowledge of data literacy, this support must focus on the pedagogical content knowledge (PCK) required to implement and support student learning. This study sought to add an extra treatment to an existing STEM integration PD which focused specifically on teachers’ PCK for data literacy. There is a major dearth of research on PCK for data literacy. Therefore, this study built on the limited research done on PCK for STEM integration and for statistics education to begin to develop an understanding of PCK for data literacy, an under-explored concept. This was an exploratory research multiple case study of four secondary school science teachers in an urban school district, who participated in the existing bioinformatics summer PD, then engaged in approximately 20 hours of workshop sessions focused on PCK development throughout the school year as they taught the bioinformatics unit. The initial findings show that there are unique components of PCK for data literacy that are different from those for science education. The participating teachers were able to surface their knowledge of student understanding of data and strategies for teaching with and about data to define a number of components of PCK that begin to build a framework for what PCK for data literacy might look like in a generalized form that could be used to support additional teachers seeking to growth their ability to teach with complex data. Additionally, strategies used in the extension PD, such as CoRes and video reflections were shown to offer support for teachers in their implementation of authentic data literacy in their classrooms
Dismantling The System: Unpacking Racism\u27s Impact On Inequities In Behavioral Health, Healthcare Utilization, And Access To Care
Get PDFIdentifying how the many elements of structural racism affect racial and ethnic health inequities remains an ongoing challenge. Although a growing body of work primarily focuses on structural racism\u27s impact on population health outcomes, this dissertation examines structural racism\u27s role in shaping inequities in behavioral health outcomes, behavioral healthcare use, and behavioral healthcare access. I argue that the complex features of structural racism work together to produce health inequities. First, I explore the relationship between self-reported racial and ethnic classification – which I conceptualize as placement in the racial hierarchy relative to whiteness – and inequities in behavioral health outcomes by analyzing a national survey of mental illness and substance misuse. Following the tenets of critical theories of race, I view each racially and ethnically classified group\u27s place in the racial hierarchy as a measure of how vulnerable they are to racism. Next, I consider how placement in the racial hierarchy shapes inequities in behavioral healthcare use by examining a national survey of tobacco and health. Finally, I build on the findings from these two lines of inquiry by using political, healthcare, and economic data sources to investigate whether the level of racial and gender equity in U.S. counties is associated with access to mental healthcare. This dissertation demonstrates that structural racism\u27s components, including inequities in healthcare treatment, the threat of harm from the criminal justice system, and histories of discrimination, can affect behavioral health outcomes. In addition, the dissertation shows that anti-Black racism, codified into health and drug policies, shapes inequities in behavioral healthcare use and geographical access to mental healthcare. Overall, this dissertation highlights that by unpacking the features of structural racism, research in this area can contribute to dismantling this system
Abyssinia To Ethiopia: Slavery, Race, And The Transition From Empire To Nation, 1855-1957
No full textThis dissertation examines the role of slavery to the development of the modern Ethiopian imperial state from the beginning of the reign of Emperor Tewodros II in 1855 until the promulgation of the 1957 Penal Code under Emperor Haile Selassie. Drawing upon a wide range of sources including European travelogues, Amharic literature, modern Ethiopian art, and legal records, it argues that slavery played more than an economic role in modern Ethiopian history. Slavery informed nineteenth and early twentieth century racial imperial hierarchies and underlined cultural notions of progress and civilization, while the abolition legislation of the twentieth century attempted to re-make Ethiopian subjects into citizens. Ethiopian imperial hierarchies organized the newly expanded empire into religiously defined racial hierarchies, which by the end of the nineteenth century informed and were shaped by a growing global color line. European travelers and Ethiopian imperial forces depended on enslaved and freed guides and translators from the borderlands to navigate these journeys and these borderland individuals shaped imperial and global racial logics. In the early twentieth century, Ethiopian intellectuals and artists grappled with their own place in global racial hierarchies and used their writing and art to assert their own notions of racial difference and belonging—often using enslaved black individuals as a foil for ‘civilized’ Christian Abyssinians. By the 1920s Ethiopian abolition legislation, influenced by international pressure at the League of Nations, attempted to re-make enslaved and freed Ethiopians into citizens. The promise of full citizenship and abolition for enslaved individuals remained elusive until the 1942, when the newly restored imperial government underwent a campaign to enforce abolition measures in the borderlands after the Italian occupation (1936-1941). Pardon petitions show a concerted effort to punish slavers in the 1940s, but the re-consolidated state emerged with a carceral regime increasingly concerned with controlling the movement of marginalized individuals. Though the state and intellectuals embraced Black internationalism and pan-Africanism after the Italian occupation, the imperial state failed to resolve its foundational religious-racial hierarchies of enslavement
Aristotle On Rhetoric
Get PDFAristotle’s Rhetoric is a technical handbook for how to persuade a public audience about what is good, just, and noble. The goal of this dissertation is to explain why Aristotle thought this ability was a kind of knowledge, a craft (technē), distinct from both political expertise (politikē) and dialectical expertise (dialektikē). I aim to do this by giving an interpretation of the norms governing rhetorical persuasion. Like his conception of dialectic, Aristotle’s conception of rhetoric is primarily governed by epistemological norms: the excellent orator is someone who can present an audience with good reasons for believing some conclusion. But, I argue, these norms are specific to the subject matter for which rhetoric is needed: matters requiring public deliberation and judgment